Gun perforator



Nov. 21, 1950 P. w. MARTIN 2,530,833

GUN PERFORATOR Filed Sept. 14, 1944 2 Sheets-Sheet 1 Nov. 21, 1950 P. w. MARTIN 2,530,333

GUN PERFORATOR Filed Sept. 14, 1944 2 Sheets-Sheet 2 J 24a 25d 1 Patented Nov. 21, 1950 GUN PERFORATOB Philip M. Martin, Huntington Park, Calif., as-

signor to McCullough Tool Company, Vernon, Calif., a corporation of Nevada Application September 14, 1944, Serial No. 554,105

This invention relates to the art of perforating oil well casing to provide passages for the flow of oil into the casing, and has as its object to provide an improved method and gun for such perforating.

One of the objects of the invention is to improve the efllciency of utilization ofthe explosive power of the charge employed to propel the projectile from the barrel of the gun. The present invention contemplates a simple method of achieving an increase in firing power.

The invention has as its basic concept exploding the propellant charges by compressing the propellant charge from the outer or discharge ends of the firing barrels. This may be done by driving the projectiles rearwardly so as to compress the propellant charges to the point where they are exploded. The compression of the propelling charges thus achieved, greatly increases the effectiveness of the propelling explosion and thereby gives the projectile a higher velocity and more penetrating power.

Another object of the invention is to provide a perforating gun in which the firing action may be transmitted automatically in succession to all of the barrels thereof. Another object of the invention is to provide a perforating gun in which there is a continuous channel of communication between the barrels which makes it possible to transmit an igniting flame or concussion in succession to all barrels, and yet in which the propelling charges are confined in chambers which are isolated completely from each other.

by their respective projectiles so that the explosions of the propelling charges may be completely concentrated against the projectiles.

Another object is to provide a simple, inexpensive easily operated and yet effective apparatus for implementing the novel method herein contemplated.

Further objects and advantages of the invention will be brought out in the following part of the specification.

Referring to the drawings which are for illustrative purposes only,

Fig. 1 is a longitudinal sectional view of a portion of an oil well in which there is positioned, ready for use, a perforating gun embodying the invention;

Fig. 2 is a detailed sectional view of a portion of the gun showing one of the barrels thereof in longitudinal section;

Fig. 3 is an elevation, partly'sectioned. of another portion of the gun, illustrating the mechanism for starting the train of detonative action;

31 Claims. (Cl. 164-0.5)

Fig. 4 is a transverse sectional view of the gun taken on the line 44 of Fig. 2;

Fig. 5 is an elevational view of portions of the gun embodying a modified form of the invention;

Fig. 6 is a transverse sectional view of a portion of the gun shown in Fig. 5, taken through one of the gun barrels thereof;

Fig. 7 is a detailed sectional view taken longitudinally through one of the barrels of a further modification of the invention;

. Fig. 8 is a transverse sectional view of a gun embodying a further modification of the invention; and

Fig. 9 is a longitudinal sectional view, taken on the line 9-9 of Fig. 8.

As an example of one form in which the invention may be embodied, I have shown in Figs.

1, 2, 3, and 4 a perforating gun ll attached to the lower end of a string of drill pipe l2 which is suspended in a well casing [3.

In accordance with this invention, the gun ll comprises a body It in the form of a bar of steel or other material having the required strength, and ,the barrels I! are formed by drilling cylindrical holes in the body l6. In order to load the individual barrels, it is only necessary to insert into the barrels, in the following order, first, a propelling charge ll} of gun powder or other suitable explosive material (a low velocity powder is suitable), the projectile IS, a plug 20 of soft rubber or the like, having a concavity 2| fitting the nose of the projectile l9, and the detonating charge 22 adapted to produce a detonating type of explosion which, reacting against the body of liquid (such as water), which is usually present in the bottom of the well as indicated at 23, Fig. 1, will drive the plug 20 and projectile l9 rearwardly in the barrel ll, compressing the propelling charge It to the point where it is exploded. The powder of the propelling charge I 8 has a gaseous medium such as air interspersed among the grains of the powder, which gaseous medium rises to ignition temperature when it is instantly The detonating charge 22 may comprise simply a short length of primer cord, or may be in the form of a pellet or capsule of any known detonating material, or may, as shown in Fig. 6, be simply a quantity of powder poured into the barrel.

As a means of setting off the priming explosion, a length of priming cord 24 is wound about the gun body IS in a helical groove 25 formed in the body IS in communication with the discharge ends of the firing barrels II. The lower end of the priming cord may be secured to the body It in any suitable manner, for example, by clamping it under a wire loop 26. The upper end of the cord is attached to a suitable detonator, such as'the blasting cap 21, mounted in an opening 28 in the upper end of'the'body l6, and adapted to be set off by dropping a go-devil l through the drill pipe.

In the use of the invention, the individual barrels I! are loaded in the manner herelnbefore described; and the length of priming cord 24 is then wound around the body is in the groove 25, and its ends suitably secured, with vthe upper end secured in the detonator cap 21.

The priming cord then serves to hold the respective chargesin the barrels ll while the gun is lowered into the well to the location where the perforation is to be made. The go-devil" i5 is then dropped through the drill pipe to contact the cap 21, thus detonating the priming cord 24%. The priming cord, detonating throughout its length, will set ofi. the several priming charges 22, the explosion of which, assisted by the explosion of the priming cord, and reacting against the body of liquid 23 as previously stated, will drive the several projectiles as. rearwardly in the barrels ll, compressing the projecting charges it to the point where they are exploded, and the resulting series of projecting explosions will drive the projectiles out of their barrels so as to perforate the casing with a series spaced perforations.

One of the important advantages of the invention is that it permits the barrels ill to be arranged suilicientlyclose together to obtain the desired closeness of spacing of the perforations. Previously it has been the practice, with guns in which the barrels were necessarily much more widely spaced, to make one perforation or a series of perforations, and then, by moving the gun, to attempt to place another perforation or series of perforations in positions of desired closeness to the original perforations. It has been impossible to obtain accuracy or uniformity of spacing by this method. The present invention solves the problem in a very simple manner.

The igniting cord 24, instead of being a primer cord adapted to produce a violent detonation, may be a slower burning type of fuse adapted, nevertheless, to ignite, in succession, the several priming charges 22 of detonating material.

As another alternative means of igniting the priming charges, the-invention may employ an electric conductor 24a, wound around the body Ilia in the helical groove 25a which is spaced slightly from the barrels H0. The conductor 24a may be provided with a series of branching leads 29, each having at its end a plug 30 adapted to be inserted in a respective barrel Ila and having an igniter filament 3| adapted to be grounded against the body Ilia as shown in Fig. 6.

The plug 30 may be employed for the secondary function of sealing the barrel, thus e hatin the plug 20.

of uniformly If the priming charge 22 is of a sufficiently violent type of detonating material, the gun of Fig. 1 may be operated successfully ina dry hole,

using only the resistance of its own developed gases, backed. up by the surrounding atmosphere, to transmit a driving force to the projectile.

Concentrated compression of only a portion of the propelling charge may be utilized for firing the same, as shown in Fig. "I. Here a projection 34, formed as an extension of the projectile l9b, is extended into the body of powder lab in an enlarged chamber 35 in the rear of the barrel Mb.

The invention also contemplates employing the explosion of the priming cord as the sole meansfor producing the priming explosion.

Instead of winding the priming cord around the external surface of the gun body, a single straight length of priming cord 24d, as shown in Figs. 8 and 9, may be extended through a longitudinal bore 25d, parallel to the longitudinal axis of the body iGd and offset from said axis so as t avoid intersection with any of the barrels lld. Through connecting passages 31, the explosion in the bore 25d may be transmitted to the discharge ends of the barrels l'ld so as to ignite priming charges therein, or the explosion of the primer cord may be applied directly to the forward ends of the respective projectiles. Sealing plugs 20d are, in this case, driven into the forward ends of the barrels lid.

I claim as my invention:

1. A method of igniting a propellant charge be= hind a projectile in a gun barrel comprising: producing a pressure in the outer end of the barrel and employing said pressure to drive the projectile rearwardly in the barrel to explode said charge.

2. A method of igniting propellant charges behind projectiles in a plurality of barrels of a tube perforating gun, comprising: producing pressure in the barrels ahead of the projectiles so as to drive the projectiles rearwardly in the barrels and compress the respective charges, causing the charges to explode and drive their re- 5 spective projectiles outwardly.

3. A method of perforating a well casing which comprises: lowering into the well a gun having a barrel loaded, in the order indicated from the rear end to the discharge end thereof, with a propelling charge, a projectile, and a priming charge,-

exploding the priming charge so as to drive the projectile rearwardly, and utilizing the compression that is thus set up in the propelling charge to explode the latter, thereby to drive the projectile out of the barrel to perforate said well casing.

4. A method of perforating a well casing containing a body of fluid which comprises: lowering to asubmerged position in said body of fluid, a perforating gun having a firing barrel loaded with a projectile, a propelling charge rearwardly of the projectile, and a primer charge forwardly of the projectile, exploding the primer charge while the gun is thus submerged so as to proing charge being of a character adapted, upon explosion, to drive the projectile rearwardly suiliciently to compress the propelling charge to the point of explosion of the latter, whereby to propel the projectile from the barrel.

6. A loaded gun comprising: -barrel, a projectile therein, a propelling charge disposed between the projectile and the rear end of the barrel, and a priming charge disposed between-the projectile and the discharge end of the barrel, said priming charge being of a character adapted, upon ignition. to drive the projectile rearwardly sufliciently to compress the propelling charge to the point of explosion, whereby to propel the projectile from the barrel.

7. A loaded well casing perforating gun comprising an elongated body having a plurality of transverse barrels therein, said barrels being integral with said body and having closed rear ends, said barrels each being loaded with a projectile therein and a propelling charge disposed between the projectfle and the closed rear end of the barrel; and means for'producing between the projectile and the front end of the barrel, a pressure adapted to drive the projectile rearwardly to com press the propelling charge to a point of explosion of the latter.

8. A gun assembly, comprising: a gun body structure defining a plurality of laterally directed gun bores; bullets in said gun bores; concussion responsive explosive means in said gun bores rearwardly of said bullets; and detonation means in front of each bullet.

9. The method of discharging a projectile from a gun bore which comprises the steps of explod- -ing an explosive charge in front of the projectile to first force the projectile rearwardly in the gun bore. and exploding a second charge rearwardly of the projectile by the concussion from the explosion of the first explosion of the first explosive charge.

10. A gun assembly comprising: a gun body structure defining a plurality of laterally directed gun bores; bullets in said gun bores; concussion responsive explosive means in said gun bores rearwardly of said bullets; and explosive means in each gun bore in front of the bullet therein.

11. A gun assembly comprising: a gun body structure defining a plurality of laterally directed gun bores; bullets in said bores; explosive means in said bores rearwardly of said bullets; and explosive means in front of each of said bullets.

12. A gun assembly ofthe character described, comprising: a body having a plurality of firing barrels extending in from the surface thereof; a projectile in each of said barrels; a propellant charge adjacent the rear end of each of said projectiles adapted to beexplode'd by compression; a firing charge adjacent the outer end of each of said projectiles; displaceable means closing the outer ends of said barrels; electrical means in the outer ends of said barrels for firing said firing charges; and means for conducting electric current to said electrical means to fire said firing charges whereby said projectiles will be driven back so as to compress and explode said propellant charges. p g

13. A gun assembly of the character described, comprising: a body having a plurality of firing barrels extending in from the'surface thereof; a projectile ineach of said barrels; a propellant charge adjacent the rear endof each of said projectiles adaptedto beexploded by compression; a firing charge adiacent'the outer end of each of said projectiles; displaceable means closing the outer ends of said barrels; electrical igniting means inthe outer ends of said barrels for firing said firing charges; and means for conducting electric current through said closing means to actuate said igniting means so as to fire said firing charges whereby said projectiles will be driven back so as to compress and explode said propellant charges. I j

14. A gun assembly of the character described, comprising: a body having a plurality of firing barrels extending in from the surface thereof; a projectile in each of, said barrels; a propellant charge adjacent the rear endof each of said projectiles adapted to be exploded by compression; a firing charge adjacent theouter end of each of said projectiles; electrical means in the outer ends of said barrels for firing said firing charges; and means for conducting electric current to said electrical means to fire said firing charges whereby said projectiles will be driven back so as to compress and explode said propellant charges.

15. A gun assembly of the character described, comprising: a body having a plurality of firing barrels extending in from the surface thereof; a projectile in each of said barrels; a propellant charge adjacent the rear end of each oflsaid projectiles adapted to be exploded by compression; a firing charge adjacent the outer end of each of said projectiles; electrical means in the outer ends of said barrels for firing said firing charges; and means extending along the exterior of said perforating gun for conducting electric current to said electrical means to fire said firing charges whereby said projectiles will be driven back so as to compress and explode said propellant charges.

16. A gun assembly of the character described, comprising: a body having a plurality of firing barrels extending in from the surface thereof; a projectile in each of said barrels; a propellant charge adjacent the rear end of each of saidprojectiles adapted to be exploded by compression; a firing charge adjacent the outer ends of each of said projectiles; displaceable means closing the outer ends of said barrels; electrical igniting means in the outer ends of said barrels for firing said firing charges; and means extending along the exterior of said perforating gun for conducting electric current through said closing means to actuate said igniting means so as to fire said firing charges whereby said projectiles will be driven back so as to compress and explode said propellant charges. 17. A gun assembly of the character described, comprising: a body having a, plurality of firing barrels extending in fromthe surface thereof and a conductor receiving channel in the exterior thereof; a projectile in each of-sald barrels; a propellant charge adjacent the rear end of each of saidv projectiles adapted to be exploded by compression; a firing charge adjacent the outer end of each of said projectiles; displaceable means closing the outer ends of said barrels; electrical means in. the outer ends of said barres for firing said firing charges; and conductor means extending at least in part through said channel for conductingelectrlc currentto said electrical means to fire said firing charges whereby said projectiles :will be drivenback so as to compress and explode'said propellant charges. 18. A gun assembly of the character described, comprising: a body having a plurality of firing barrels extending in from the. surface thereof and a conductor receiving channel in the exterior thereof; a projectile in each'of saidbarrels; a

propellant charge adjacent the rear. end of each of said projectiles adapted to be exploded by compression; a firing charge adjacent the outer end of each of said projectiles; electrical means in the outer ends of said barrels for firing said firing charges; and conductor means extending at least in part through said channel for conducting electric current to said electrical means to fire said firing charges whereby said projectiles will be driven back so as to compress and explode said propellant charges.

19. In a-gun assembly, a gun body structure defining a gun bore; a bullet in said bore; propellant explosive means rearwardly of said bullet; closure means extending across said gun bore adjacent the muzzle end thereof; explosive meansin said gun bore between said closure means and said bullet, said explosive means comprising an explosive charge and ignition means therefor; and means extending through said closure means for actuating said ignition means.

20. A gun assembly comprising: a bod having a firing barrel extending in from the surface thereof; a projectile in said firing barrel; a propellant charge adjacent the rear end of said projectile; a firing charge adjacent the outer end of said projectile; displaceable means closing the outer end of said barrel; electrical means in the outer end of said barrel for firing said firing charge; and means for conducting electric current to said electrical means to fire said firing charge.

21. A gun assembly comprising: a body having a firing barrel extendin in from the surface thereof; a projectile in said firing barrel; a propellant charge adjacent the rear end of said projectile; a firing charge adjacent the outer end of said projectile; electrical means in the outer end of said barrel for firing said firing charge; and means for conducting electric current to said electrical means to fire said firing charge.

22. In a gun assembly wherein a propelling charge is fired by driving the projectile rearwardly so as to compress the propelling charge, the combination of: a un structure having a gun barrel and a propelling charge chamber communicating with its rear end; a propelling charge in said chamber; a projectile in said barrel spaced from the outer end of said barrel; a wall closing the outer end of said barrel to prevent entry thereinto of external pressure; a firing charge between said projectile and said wall; electrically actuated igniting means for said firing charge between said wall and said projectile; and means extending through said wall for conducting electic current to said igniting means.

23. In a gun assembly wherein a propelling charge is fired by driving the projectile rearwardly so as to compress the propelling charge, the combination of: a gun structure havinga gun barrel and a propelling charge chamber communicating with its rear end; a propelling charge in said chamber; a projectile in said barrel spaced from the outer end of said barrel; a wall closing the outer end of said barrel to prevent entry thereinto of external pressure; a firing charge between said projectile and said wall; a filament adjacent the inner face of said wall for igniting said firing charge; and means extending through said wall for connecting the filament with a source of current.

24. In a gun assembly, wherein a propelling charge is fired by driving the projectile rearwardly so as to compress the propelling charge, the combination of: a gun structure having a gun barrel and a propelling charge chamber communicating with its rear end; a propelling charge in said chamber; a projectile in said barrel spaced from the outer end of said barrel; a wall closing the outer end of said barrel to prevent entry thereinto of external pressure; a firing charge between said projectile and said Wall; and means operative through said wall for exploding said firing charge.

25. In a gun assembly wherein a propelling charge is fired by driving the projectile rearwardly so as to compress the propelling charge, the combination of: a n structure havin a gun barrel and a propelling charge chamber communicating with its rear end; a propelling charge in said chamber, said propelling charge comprising a mass of powder grains interspersed with a gaseous medium; a projectile in said barrel spaced from the outer end of said barrel; a wall closing the outer end of said barrel to prevent entry thereinto of external pressure; a firing charge between said projectile and said wall; and means operative through said wall for exploding said firing charge.

26. In a gun assembly wherein a propelling charge is fired by driving the projectile rearwardly so as to compress the propelling charge, the combination of a gun structure having a gun barrel and a propelling charge chamber communicating with its rear end; a propelling charge in said chamber, said propelling charge comprising a mass of powder grains interspersed with a gaseous medium, and being installed under no compression other than that of the atmosphere; a projectile in said barrel spaced from the outer end of said barrel; a wall closing the outer end of said barrel to prevent entry thereinto of external pressure; a firing charge between said projectile and said wall; and means for exploding said firing charge.

27. In a gun assembly wherein a propelling charge is fired by driving the projectile rearwardly so as to compress the propelling charge, the combination of: a gun structure having a gun barrel and a propelling charge chamber communicating with its rear end; a propelling charge in said chamber, said propelling charge comprising a mass of powder grains interspersed with a gaseous medium; a projectile in said barrel spaced from the outer end of said barrel; means for preventing external pressure from moving said projectile so as to apply pressure to said propelling charge; and means for driving said projectile rearwardly in said barrel so as to compress the contents of said propelling charge chamber, to ignite said propellin charge.

28. The method of controlling the ignition of the propelling charge in a gun wherein a projectile is driven rearwardly against the propelling charge disposed in a propelling charge chamber so as to cause ignition of the propelling charge, comprising the steps of: disposing the propelling charge in the propelling charge chamber in the form of a mass of grains interspersed with spaces filled with gas; holding the projectile from inward movement until such time as the firing of said propelling charge is desired; and firing said charge by moving said projectile rearwardly so as to compress said propelling charge and bring said gas to an ignition temperature.

29. The method of controlling the ignition of the propelling charge in a gun wherein a projectile is driven rearwardly against the propelling charge disposed in a propelling charge chamber so as to cause ignition of the propelling charge, comprising the steps of: disposing the propelling charge in the propelling charge chamber in the form of explosive and gas adapted upon compression to rise to an explosive igniting temperature; holding the projectile from inward movement until such time as the firing of said propelling charge is desired; and firing said charge by moving said projectile rearwardly so as to compress said propelling charge and bring said gas to an ignition temperature.

30. The method of controlling the ignition of the propelling charge in a gun wherein pressure is applied so as to cause ignition of the propelling charge, comprising the steps of: disposing the propelling charge in the propelling charge chamher in the form of a mass of grains interspersed with spaces filled with gas; holding pressure from said propelling charge until such time as the firing of said propelling charge is desired; and firing said charge by applying pressure to the outer portionof said gun barrel to compress said propelling charge and bring said gas to an ignition temperature.

31. The method of controlling the ignition oi. the propelling charge in a gun wherein pressure is applied so as to cause ignition of the propelling charge, comprising the steps of: disposing the charge until such time as the firing of said pro-' pelling charge is desired; and firing said propelling charge by applying pressure to the outer portion of said gun barrel to compress said propelling charge and bring said gas to an ignition temperature.

PHILIP W. MARTIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,130,138 Kniss Sept. 13, 1938 2,142,583 Yarbrough Jan. 3, 1939 2,250,055 Alexander July 22, 1941 2,266,343 Spencer Dec. 16, 1941 2,297,038 Turechek Sept. 29, 1942 2,309,835 Fearon Feb. 2, 1943 2,331,057 Spencer Oct. 5, 1943 FOREIGN PATENTS Number Country Date 2,755 Great Britain Oct. 13, 1862 

